The following abbreviations and terms are herewith defined:
3GPP third generation partnership project
DL downlink
Node B base transceiver station or other access node
E-DCH enhanced dedicated channel
E-DPCCH E-DCH dedicated physical control channel
E-DPDCH E-DCH dedicated physical data channel
E-TFC E-DCH transport format combination
E-TFCS E-DCH transport format combination set
E-UTRAN evolved UTRAN
FDD: frequency division duplex
HSUPA high speed uplink packet access
LTE long term evolution of 3GPP
Node B base station or similar network access node
TDD time division duplex
UE user equipment (e.g., mobile equipment/station)
UL uplink
UMTS universal mobile telecommunications system
UTRAN UMTS terrestrial radio access network
WCDMA wideband code division multiple access
One of the 3GPP wireless access technologies is WCDMA/HSUPA. As currently specified in 3GPP release 6 (and release 7) the uplink gain factors for E-DPDCH are calculated according to the E-DCH Transport Format Combination (E-TFC). The gain factor for E-DPCCH, and a set of reference gain factors (up to eight) for the E-DPDCH, namely the values, are signaled by the UTRAN. Up to 127 E-TFCs may exist and be used and, thus, for those E-TFCs which are not in the set of reference gain factors gain factors must be computed by the UE and BTS using an equation defined in 3GPP TS 25.214 (Technical Specification Group Radio Access Network; Physical layer procedures (FDD), which is attached to the priority document as Appendix A (sections 5.1.2.5A through 5.1.2.6)). Thus, for each E-DPDCH data rate there exists a specific network configured power offset between the E-DPCCH/DPCCH and the E-DPDCH/DPCCH.
The gain factor is directly related to the amplitude of the channel that is transmitted from the UE towards the NodeB. The power of the DPCCH is controlled by the NodeB by the power control commands (UP, DOWN), and the power of other channels that are going to be transmitted are set according to rules defined in 3GPP TS 25.214, section 5 and are constrained by the total transmit power available in the UE.
Specifics concerning the gain factors and how they are computed are currently specified at 3GPP TS 25.214, section 5.1.2.5B (setting the UL E-DPCCH and E-DPDCH powers relative to E-DPCCH power).
In the Release 6 specification of 3GPP the gain factor of the E-DPCCH is signaled from the NodeB to the UE. Next the UE shall execute an E-TFC selection process in order to determine the E-TFC and the E-DPDCH gain factor(s) are calculated according to the determined E-TFC. The E-DPCCH gain factor does not depend on the E-DPDCH gain factor(s) in this case.
In order to support higher data rates the range of E-DPDCH gain factor(s) is greater in the Release 7 than in the Release 6. However, this also requires that the range of E-DPCCH gain factor is also greater in the Release 7 than in the Release 6. Therefore, two operational modes are available in the Release 7 specification: E-DPCCH normal mode and boost mode. The purpose of the boost mode is to provide more power for E-DPCCH in order to offer an enhanced reference signal for the BTS. The requirement to use boost mode is signaled to the UE by means of an E-TFCI boost parameter, designated as E-TFCIec,boost.
When the E-DPCCH boost mode is not configured the E-DPCCH gain factor is the signaled one as in the Release 6. When the E-DPCCH boost mode is configured the E-DPCCH gain factor depends on the E-DPDCH gain factor(s) and on the traffic to total pilot offset parameter that is designated as ΔT2TP and signaled to the UE. The determination of E-DPCCH and E-DPDCH gain factors is defined at 3GPP TS 25.214, section 5.1.2.5A through C, reproduced at Appendix A of the priority document. Also in this case the E-DPCCH gain factor is signaled to the UE, but the signaled E-DPCCH gain factor is the minimum gain factor the E-DPCCH is allowed to obtain. After the channel gain factors are set, the total transmit power the UE is going to use is at maximum the maximum allowed transmit power for the UE. However, if the total transmit is close enough, or equal to the maximum allowed transmit power and a “power up” command (UP) were received and applied at the UE the total transmit power would exceed the maximum allowed transmit power. In order to UE not to exceed the maximum allowed transmit power yet obeying the “power up” command the specification defines a scaling process (E-DPDCH scaling) the UE is required to apply when the maximum transmit power would be exceeded.
According to 25.214, section 5.1.2.6 the “UE must first reduce E-DPDCH transmit power to minimum, and, if this is not enough, to proceed further with equal scaling of all channels in order to guarantee that the maximum allowed transmit power is not exceeded”. In practice this means that before a next transmission event is going to take place the UE must calculate the total transmit power (P_tx) that would be used in the next transmission event. The calculated total transmit power (P_tx) is compared with the maximum allowed transmit power (P_max) and if the calculated total transmit power (P_tx) would exceed the maximum allowed transmit power (P_max) the scaling of E-DPDCH channel(s) is applied. It is also important to notice that in its current form the Release 7 specification does not disclose anything about the E-DPCCH.